Blasting agents containing guar gum

ABSTRACT

Granular water-resistant blasting compositions containing a water-soluble inorganic oxidizing agent, fuels, densifiers and guar gum.

O United States Patent 1151 3,640,784

Yancik et al. 1451 Feb. 8, 1972 [54] BLASTING AGENTS CONTAINING [56]References Cited GUAR GUM UNITED STATES PATENTS [72] lnventors: JosephJ. Yaneik, Creve Coeur; Roy E.

5mm; Paul H. Rydhmd, both of St 3,432,371 3/1969 Grant ..149/44x FOREIGNPATENTS 0R APPLICATIONS z t. [73] 669,074 8/1963 Canada ..149/43 1Mar-5, 1969 1,143,902 2/1969 Great Britain ..149/44 211 Appl. No.1804,682

Primary Examiner-Leland A. Sebastian 52 u.s.c1. ..149/43,149/21, 149/42,ff f' Bmsk and 149/112, 149/113 1511 1111.121 ..C06b l/04,C06b 11/00,CO6bl9/04 ABSTRACT [58] meld ofsemhw Granular water-resistant blastingcompositions containing a water-soluble inorganic oxidizing agent,fuels, densifiers and guar gum.

3 Claims, No Drawings "BLASTING AGENTS CONTAINING GUAR GUM Thisinvention relates to dry; free-flowing granular blasting compositionsand-particularly to water-resistant compositions containing apredominant proportion of a water-soluble inorganic oxidizing salt. v

' Armno'nium -nitrate has been used for many years asthe chief componentin the preparation of blasting agents. Although ammonium nitrate andother water-soluble inorganic oxidizing salts serve very well in'themanufacture of efficientand economical blastingag'ents, they present aserious problem because they are readily soluble in water and veryhygroscopic. It is therefore necessary to make some provision toeliminate their contact with water or, on the-other hand, to rriinimizethe'efi'ect of water on them. Prior to the advent of thepresentinvention; several methods have'been used to exclude water fromexplosive or blasting compositions based on water-soluble inorganicoxidizing salts, such as ammonium nitrate.= In severalinstanceswaterproof cartridges" have been succe'ssfullyemploye'dbut theymaterially increase the cost of the compositions and present someoperational difficulties. Several attempts havealso been made towaterproof the compositions themselves. Such methods include theincorporation of nitrocellulose and liquid nitric esters, coating thewatersolublesalts with waxes, resins, asphalts and other waterrepellantsfandthe incorporation of gel-forming water dispersiblestarches." More recently industry has resorted to explosives of theslurry type inwhich water is intentionally added to the composition. Theslurry explosives are in essence a suspension of solids-including'undissolved oxidizing salts in a saturated aqueous solution of thesalt-.While'the slurry explosives have experienced some commercialsuccess," they have one inherent and serious disadvantagethe presence ofthe required water normally 8 percent or more even when liquid extenderssuch as forrnamideare'used'detracts appreciably from their explosivestrength per unit weight. Thus, all prior art compositions-utilizingwater-soluble inorganic oxidizing salts have met 'withvarying'degrees ofsuccess but each has-had its shortcomings.

S Accordingly,'an object of this invention is to provide novelwater-resistant blasting compositions overcoming the shortcomings of theprior art. A more specific object is to provide improved granularfree-flowing water-resistant blasting compositions containing apredominant proportion of a watersoluble inorganic oxidizing salt.

' It has nowbeen found in accordance with the present-inventionthat=superior and advantageous-results are achieved by the preparationof-blasting-compositions containing within well-defined limits ammoniumnitrate, a solid-densifying agent 'includingvferrophosphorus,ferrosilicon and ferromanganese,

a self-'complexing guar. gum, glycerine or ethylene glycol, a metallicsensitizer and source of high energy including alu- -rninum,- magnesiumand alloys thereof, a water-resistant agent includingstearicacid-alkaline earth stearates and various types of waxes, and an oxide'orhydroxide 'ofan alkaline earth metal or ofzinc to serve as a temperaturestabilizer. 'All components contribute to the'successful functioning ofthe compositions 'of the present inventionand are present'withinwelldefined limits. F The approximate ranges of each component that canbe utilized in preparing the novel compositions of the present in- Ivention are 54 to 95 percent ammonium nitrate, up to 10 percentferropho'sphorus, ferrosilicon or ferromanganese, up to 5percentethylene glycol, glycerine oraliphatic alcohols (C, *k to 5percent s'elf-complexing guar gum, to 21 9% percent ofaluminum-magnesium or alloys thereof, up to 2 percent stearit: acid, analkali metal stearate or a wax, and up to 3 percent of'an oxide(Jr-hydroxide of an alkaline earth metal orzinc. in some instancesminoramounts'-( up to about 2 percent) of fuel oil'can beadded to adjustthe oxygen balance of the compositionsor to facilitate preparation ofthe compositions. The above-percentage range'sarebased on the weight ofthe composition. Likewise, throughout-the specification and claims 'allproportions are expressed in parts byweight orweight percent based onthe total composition.

Although it is generally preferred to" use high-density ammonium nitrateof the type described, for example, in US. Pat: No. 3,030,179, moreporous and low-density ammonium nitrate products can inmost instances beused withequal success. Likewise, the present invention is not limitedto the physical form of the ammonium nitrate employed. Thus the nitratecan be prilled, granular or flaked-but optimum results have "beenachieved with compositions containing com minuted ammonium nitratevarying in size with at least 60 percent of the particles having a majordiameter-less than 1.68

mm. (12 mesh USS); In fact, commerciallyavailable prills which normallypass through a 12 mesh screen and are retained on a mesh screen-canconstitute up to about 50 percent of the total ammonium nitrate in thepresent compositions with the remainder of the ammonium nitrate beingcomminuted'and-having theparticle size distribution indicated above.The-ammonium nitrate in the compositions of the present invention canbereplaced in whole or in partby nitrates, chlorates and perchlorates ofthe alkali metal and alkaline earth metal, and ammonium. Thus, suitablesubstituents include sodium'nitrate, calcium nitrate, magnesium nitrate,ammonium'chlorate, ammonium perchlorate and the like. For thesake ofclarity and convenience the water-soluble inorganic oxidizing salt willbe referred to hereinafter as ammonium nitrate.

The aluminum serves adual function and is present in two distinct forms.From about onefourth to 5 percent of the aluminum is in the'form of apowder having a-particle size sufficiently small to passthrough a325'mesh screen. This finely divided aluminum serves primarily as asensitizer and insures that the compositions will retain theirsensitivity even in the presence of water. The remainder of thealuminum, that is, from about one-half to about 20 percent, is in theform of granules with aparticle size finer than 8 mesh or chopped foiland serves as a high-energy source. The foil has a thicknessof'about0.05 mm. and an average major dimension of 2.4 mm. Both the chopped andgranular materials have specific areas of at least about 0.2 sq. metersper gram and densities between 16 and 80 pounds per cubic foot. Thealuminum'can be replaced by magnesium or aluminum-magnesium alloys.

The preferred solid densifier is ferrophosphorus. This material canhowever be replaced in whole or in part by ferrosilicon orferromanganese. In any event, the solid densifier is in particulate formand mustbe sufficiently finely divided to pass throughan 80-mesh screen.Ferrophosphorus serves to increase the bulk density of theblastingcompositions and also as a fueland a serisitizer.

The guar gum used in accordance with the present invention must be ofthe self-complexing type. This material is commercially available underavariety of trade names and it is immaterial whether its self-complexingcharacteristics are inherent or are impartedby theaddition of one ormore crosslinking-agents. It is only necessary that the gum be capableof forming astiff gel structure when exposedto water in' the must becarefully controlled to insure that the gum will crosslink so as to forma gel upon contact-with'water in contrast to merely forming a viscousflowable 'liquidsystem. It has been found'that' in compositions of thepresent invention the pH must be maintained-between 3.5' and 7.0.Withmore acidic systems the gums deteriorate and hydrolyze, whereas above pH7 ammonia is released and the gums'fail to cross-link or form complexes.While satisfactory composition can be prepared between pH 3.5 and pH 7,it has been found that the optimum range is between pH 4.2'and pH 4.7.To maintain the required pH range it may be necessary to add a buffer.Various saltscan be used for this purpose but from the standpoint ofconvenience and economy it is preferred to use monoammonium-phosphate.The identity of the specific bufier is not critical but it is'onlynecessary that it buffers near the'pH- of the particular guar gum usedand that it is compatible with the gum.

The temperature stabilizer such as magnesium hydroxide which is presentin relatively small amounts serves to increase the high temperaturestorage stability of the present compositions by neutralizing any acidthat may be liberated when the compositions of the present invention arestored at relatively high temperatures, that is from about 80 to about110 F. Suitable temperature stabilizers include zinc oxide, calciumhydroxide, calcium oxide, barium hydroxide, and the like.

In preparing the blasting agents of the present invention it ispreferred to mix the finely divided aluminum sensitizer with liquiddensifier such as ethylene glycol or glycerine. The aluminum dust orpowder is readily wetted by the glycol and forms therewith a thinsuspension. The resultant suspension is then intimately mixed with theammonium nitrate to form a substantially homogeneous admixture. Themixing of the aluminum dust with the glycol prevents the dust frombecoming airborne and creating a potential hazard. The remainingcomponents of the compositions are then added in any desired sequenceand mixed until uniform. The compositions thus formed are dry, granularand free-flowing and have a built density of from 0.7 to 1.15. Thesematerials are well adapted for loading into conventional cartridgeswhich need not be waterproof. Since these materials are free-flowing andhave excellent water resistance, it is more advantageous to charge themdirectly into bore holes. In this way the charge can conform exactly tothe contour of the bore hole and eliminate any air pockets or gaps whichwould be present with cartridge loading. These compositions even whencharged into a damp bore hole or one containing water will retain theirsensitivity and detonation characteristics for a considerable period oftime.

The present invention and the manner in which it achieves itsadvantageous results will be more readily understood by reference to thefollowing specific illustrative embodiments thereof.

v EXAMPLE 1 About 0.5 part of -325 mesh aluminum dust was added to andsuspended in about 1 part of ethylene glycol. This suspension ofaluminum dust in the glycol was then added to about 79.5 parts ofhigh-density ammonium nitrate prills that had been previouslyroll-crushed in accordance with the procedure of US. Pat. No. 3,291,659.The ammonium nitrate and the suspension were thoroughly mixed until thesuspension had formed a substantially uniform coating on the ammoniumnitrate particles. About 8 parts of chopped aluminum foil having anaverage major dimension of 0.6 mm. and a surface area of at least 0.2sq. meters per gram, about 5 parts 80 mesh ferrophosphorus, about 2parts self-complexing guar gum, about 1.15 parts of monoammoniumphosphate, about 0.6 parts of magnesium hydroxide, and about 1 part ofstearic acid were added to the ammonium nitrate slurry admixture. Thesequence of addition of the various components is immaterial. During theaddition the components were continuously mixed and mixing was continueduntil the composition was substantially uniform. The blastingcomposition thus obtained was cap-sensitive, that is, it was capable ofbeing initiated with a No. 8 blasting cap. It was readily detonated witha V4 pound charge of 40 percent sernigelatin dynamite in contact withone end of a charge 1% inches in diameter and '7 feet long. When thusinitiated the charge propagated throughout its entire length and had adetonation rate of approximately 10,000 ft. per second.

To illustrate the water resistance of this composition, cartridges 2%inches in diameter and 24 inches long were submerged under 10 feet ofwater for 24 hours each and then initiated with a as pound pentoliteprimer. This material which had been thoroughly wetted had a detonationrate of approximately 10,500 ft. per second unconfined.

EXAMPLE 2 About 30 axial inches of a nitrocarbonitrate composition madein accordance with the present invention and consisting of approximately86.3% Ammonium nitrate 8% Aluminum granules 1% Ethylene glycol 1/2%Aluminum powder 2% Guar Gum (self-complexing) 1.2% Monoammoniumphosphate 1% Stearic acid was placed under an 1 1 foot head of water ina 6-inch diameter pipe. The charge was maintained under the water forapproximately 46 hours and then removed. A 1 pound cast pentolitebooster was placed in contact with one end of the charge 7 and a 30 inchlength of 150 gr. Primacord was positioned in contact with the other endof the charge. The booster was then initiated with a No. 6 electricblasting cap and the nitrocarbonitrate composition was completelydetonated, as evidenced by the initiation of the Primacord by thenitrocarbonitrate composition.

For purposes of comparison, about 30 axial inches of a standardnitrocarbonitrate composition consisting of approximately percentammonium nitrate, 6.4 percent aluminum granules, 10 percentferrophosphorus and 3.6 percent fuel oil was placed under a 1% foot headof water in a 6-inch pipe. A 1 pound cast of pentolite booster wasimmediately placed at the nitrocarbonitrate water interface. The chargewas left undisturbed for 3 hours and then inspected. About 18 inches ofthe nitrocarbonitrate column was no longer in a solid condition and thebooster was completely surrounded by a mixture of water, ammoniumnitrate solution, suspended aluminum and ferrophosphorus granules, andfuel oil. Upon initiation of the booster by a No 6 electric blasting capthe charge failed to denote.

EXAMPLE 3 Another nitrocarbonitrate composition in accordance with thepresent invention and consisting of approximately 40.4% Crushed ammoniumnitrate 40.0% Pn'lled ammonium nitrate 2% Guar gum 8% Aluminum granules5% Ferrophosphorus 1% Monoammonium phosphate 0.6% Magnesium hydroxide.

1% Ethylene glycol 0.5% Aluminum dust 1% Stearic acid 0.5% Fuel oil wascharged into 42 bore holes, each 12 ft. long by 1% inches in diameter,by a conventional air placement technique. The condition of the holesvaried considerably; nine of them were making from to 2 gallons of waterper minute; eighth were as filled with standing water and the remainderwere from damp to dry. After being charged, each hole was primed with aNo. 6 electric blasting cap inserted into a stick of 40 percentsernigelatin dynamite, 24 inches long and having a diameter of 1%inches. The charges in each of the holes detonated completely regardlessof the presence of running or standing water. The total powder factorwas 0.535 pounds of explosive per ton and fragmentation from the blastwas excellent. 7 7 n V A number of other compositions within the scopeof the present invention were prepared, charged and initiated in likemanner. The appropriate compositions and the sensitivity of thesecompositions both before and after being subjected to moisture are setforth below in tabular form.

TABLE Composition by weight percent Bulk mix Example Number AN Guar ALF021 MAP Mg(OH)2 Ethylene Al dust Steario Sensitivity Propagagnm glycolacid to N o. 8 E130 tion 1. 5 7 1. 15 0. 55 1 0. 1 1-DET Detonation.

2 8 5 1.1 0.56 l 0.5 1 I-DET D0. 2 8 5 1 1 0. 56 1 0. 5 1 1-DEI D0. 2 80 1. 1 0 0. 65 0. '25 1 11)El Do. 2 8 5 1. 1 0. 56 1 0. 5 1 1-DEI D0 1%8 5. 5 1. 1 0 2 1. 0 0 1DET Do 2 8 5.5 1.1 0. 1 0.5 0 1-1)E'I D0.

In the above table, the ammonium nitrate (AN) in Examples 5 and 7through was all roll-crushed in accordance with the procedure of US.Pat. No. 3,291,659; whereas the ammonium nitrate of Example 4 consistedof equal amounts of whole prills and crushed prills and the ratio ofwhole prills to crushed prills in Example 6 was 1:2.

In the above table, the tenn propagation indicates the ability of thecharge to detonate after having been pneumatically loaded into aschedule 40 steel pipe 1% inches in diameter and 7 feet long which wasinitially filled with water. In each instance the column ofnitrocarbonitrate was bottom-primed with semigelatin dynamite andinitiated with a No. 8 electric blasting cap. By contrast, aconventional AN IFO composition consisting of 94 percent prilledammonium nitrate and 6 percent fuel oil failed to propagate under thesame conditions.

While the compositions of the present invention are particularly wellsuited forbulk loading, they are also readily adaptable for cartridgeloading. In order to demonstrate this, car'- tridges 2% inches indiameter by 24 inches long were charged with a composition of thepresent invention consisting of about 81.5 percent of ammonium nitratethat had been rollcrushed in accordance with the procedure of US. Pat.No. 3,291,659, 2 percent guar gum, 8 percent aluminum granules, 5percent ferrophosphorus, 1.15 percent monoammonium phosphate, 0.6percent magnesium hydroxide, 1 ethylene glycol, 0.5 percent aluminumdust and 1 percent stearic acid. This charge had a packaged density of1.17. For purposes of comparison, a more conventional compositioncontaining about 80 percent roll-crushed ammonium nitrate, 6.4 percentaluminum, 10 percent ferrophosphorus and 3.6 percent fuel oil wascharged into cartridges of the same type to provide a charge with thepacking density of 1. 15. The loaded cartridges were punctured at bothends with a A-inch diameter hole and then soaked under a 10 ft. head ofwater for 24 hours.

In order to demonstrate the propagation capability of the compositionsof the present invention, a vertical pipe 6 ft. long and 3 inches indiameter was closed at the bottom and filled with water. A dry cartridgecharged with a composition of this invention was dropped into the pipe,a water wet cartridge placed on top of it and then another dry cartridgeplaced on top of it and then another dry cartridge. The dry cartridgewas initiated with a rpound cast of pentolite booster. Upon initiation,all three cartridges detonated completely thus illustrating the abilityof the charge to propagate a detonation wave whether the composition waswet or dry. When subjected to this same procedure, the conventionalnitrocarbonitrate failed to propagate through the wet portion of thecomposition.

Thus it is evident that the particular compositions utilized inaccordance with the present invention provide ammonium nitrate blastingagents that are not injuriously affected upon exposure to water ormoisture.

While this invention has been described with respect to various specificexamples and embodiments, it is understood that the invention is notlimited thereto and that it can be variously practiced within the sco ofthe following claims.

The embodiments o the invention in which an exclusive property orprivilege is claimed are defined as follows:

-monium phosphate; between about three-quarters and 2% percent aluminum,magnesium or alloys thereof. a predominant portion of the magnesium andaluminum being in the form of foil and the remainder being in the formof granules or finely divided foil; up to about 2 percent stearic acid,an alkali metal stearate or a wax; and between about 0 and about 3percent of a oxide or hydroxide of an alkaline earth metal or zinc; thecomposition having a pH between 3.5 and 7.0.

2. A dry, free-flowing water-resistant blasting composition having abulk density between about 0.7 and about 1.15 and comprising betweenabout 54 and about 95 percent ammonium nitrate, 60 percent of which hasa major diameter less than 1,680 microns; up to about 10 percent meshferrophosphorus; up to about 5 percent ethylene glycol; between aboutone-half and about 5 percent self-complexing guar gum; between aboutone-quarter and about 5 percent aluminum dust sufiiciently finelydivided to pass through a 325 mesh screen; between about one-half andabout 20 percent comminuted aluminum foil or granules having an averagemajor dimension of 600 microns; up to about 2 percent stearic acid; upto about 3 percent magnesium hydroxide; and between about one-quarterand 2 percent monoammonium phosphate; the composition having a pHbetween 3.5 and 7.0.

3. A water-resistant blasting composition comprising a substantiallyhomogeneous mixture of about 79.5 percent of highdensity roll-crushedammonium nitrate prills, about 0.5 percent aluminum dust, about 8percent finely divided aluminum foil, about 1 percent stearic acid,about 5 percent ferrophosphorus, about 2 percent self-complexing guargum, about 1.2 percent monoammonium phosphate, about 0.6 percentmagnesium hydroxide, and about 1 percent ethylene glycol.

Patent No. 5,640,784 Dat d February 8, 1972 Inventor(s) os ph J Yancik,et a1 It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Column 4, line 59, delete "eighth" and substitute eight and delete "1/2"and substitute therefor 2/5 In the Table spanning Columns 5 and 6, underthe heading "AN" relative to Example Number 6, delete "80.3" andsubstitute theIefOI' 801 8 "-0 Column 5, line 38, immediately after "1",insert Column 6, line 31, delete "2-l/2" and substitute therefor 21-1 2Signed and sealed this 27th day of June 1972.

(SEAL) Attest'.

EDWARD MFLETCHER,JR ROBERT GOTTSCHALK I Attesting Officer Cozmnissionerof Patents FORM PO-1050 (10-69) USCOMM-DC 60376-P69 Q US4 GOVERNMENTPRINTING OFFICE: I959 0366-334 UNITED STATES PATENT OFFICE CERTIFICATEOF CORRECTION Patent NO. 1 v Dated F r ry 197 Inventor(s) Joseph J.Yancik, et al It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 59, delete eighth" and substitute eight and delete "1/2and substitute therefor 2/3 v In the Table spanning Columns 5 and 6,under the heading "AN" relative to Example Number 6, delete "80.3" andsubstitute therefor 80.8

Column 5, line 38, immediately after "1'', insert 75 Column 6, line 31,delete "2-1/2" and-substitute therefor 21-1 2 Signed and sealed this27th day of June 1972.

(SEAL) Attest: I

EDWARD M.FLETCHER,JR. ROBERT GOITSCHALK Attesting Officer Commissionerof Patents FORM USCOMM-DC 60376-P69 U.S, GOVERNMENT PRINTING OFFICE I969O356-334

2. A dry, free-flowing water-resistant blasting composition having abulk density between about 0.7 and about 1.15 and comprising betweenabout 54 and about 95 percent ammonium nitrate, 60 percent of which hasa major diameter less than 1,680 microns; up to about 10 percent -80mesh ferrophosphorus; up to about 5 percent ethylene glycol; betweenabout one-half and about 5 percent self-complexing guar gum; betweenabout one-quarter and about 5 percent aluminum dust sufficiently finelydivided to pass through a 325 mesh screen; between about one-half andabout 20 percent comminuted aluminum foil or granules having an averagemajor dimension of 600 microns; up to about 2 percent stearic acid; upto about 3 percent magnesium hydroxide; and between about one-quarterand 2 percent monoammonium phosphate; the composition having a pHbetween 3.5 and 7.0.
 3. A water-resistant blasting compositioncomprising a substantially homogeneous mixture of about 79.5 percent ofhigh-density roll-crushed ammonium nitrate prills, about 0.5 percentaluminum dust, about 8 percent finely divided aluminum foil, about 1percent stearic acid, about 5 percent ferrophosphorus, about 2 percentself-complexing guar gum, about 1.2 percent monoammonium phosphate,about 0.6 percent magnesium hydroxide, and about 1 percent ethyleneglycol.